That's a valid point, but even still if the link was shared on Facebook then why wouldn't those people comment on Facebook instead of going to the trouble of si

That's a valid point, but even still if the link was shared on Facebook then why wouldn't those people comment on Facebook instead of going to the trouble of signing up for some site they've never been to and don't plan to participate in? Unless they were asked to sign up and add a comment of support, which isn't much better.